Forklift utilizes a lifting system to perform working procedures, such as picking up cargo, raising and lowering cargo, piling cargo and stacking cargo. After the cargo is picked up by the forklift, the forklift controls the lowering speed of the cargo by various throttling manners during the process of lowering the cargo. In this process, gravitational potential energy is totally converted into heat energy by throttle valves, which causes the temperature rise of the hydraulic system, thereby adversely affecting the reliability of the system and components and the operating efficiency of the whole forklift. With the increasingly severe shortages of international energy supply and the gradually raising awareness of environmental protection worldwide, green and energy-saving has became the future trend of technologies and products in all industries. The development makes us realize that recycling and reusing of the waste potential energy and hydraulic energy is an effective approach for energy conservation and emission reduction, and especially has a great practical significance for the forklift which performs raising and lowering actions repeatedly. A known lowering-process energy recovery system of the forklift is provided with one or two groups of external electromagnetic reversing valves to meet the requirement for switching operating oil paths during the raising and lowering processes, and generally, a single pump is used for generating electricity, thus an oil pump having a large displacement and an electric machine having a large power are required, which results in a high cost. A patent No. ZL 201120038176.8, titled “HYBRID FORKLIFT HYDRAULIC SYSTEM” and a patent No. ZL 201120038177.2, titled “ENERGY-SAVING HYDRAULIC SYSTEM OF ELECTRICAL FORKLIFT” provide the following technical solutions. A raising and lowering valve spool is further provided with a Pt port to solve the problem of the lowering oil path of the oil cylinder. A hydraulic controlled sequence valve is controlled by a pilot pressure oil path to meet the requirement for the electricity generation during the lowering process under different loads, and the electricity generation modes are determined according to the load conditions. The electricity generation is driven by a single pump, which requires an oil pump having a large displacement and an electric machine having a large power. The tilting action during the raising process is controlled by a safety valve, however the actual operating pressure in the tilting action is low, and the tilting action is frequently performed, and there is only one pressure setting, thus the system loss is great. The break system is supplied with oil by only one oil pump, which results in a high manufacturing cost. According to the technical solution of a patent No. ZL 200920200479.8, titled “HYDRAULIC SYSTEM FOR FORKLIFT”, the problem, that the braking and the steering are associated, is solved by providing a priority valve and a diverting valve, however since the oil supplies for the braking and the steering are achieved by two oil pumps respectively, the two oil pumps are required to work simultaneously once the forklift starts work, which results in a great system power loss. In this technical solution, the hydraulic oil outputted by the two oil pumps flow through the priority valve and the diverting valve, respectively, and then are converged by an EF oil path, the converged oil is supplied to a raising oil cylinder and a tilting oil cylinder for achieving the raising and tilting of a cargo fork. However, in practice operation of the forklift, the raising operation requires a large oil flow, but the tilting operation requires less oil flow, thus the oil supply with two pumps requires to provide throttling holes in a multiple directional control valve or a pipeline to control the speed of forward tilting or backward tilting, which results in a great pressure loss and a great temperature rise of the hydraulic system.